Allocation of Resources Without Limits or Throttling Affecting mcp package, versions <0.23.0
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applicationsSnyk Learn
Learn about Allocation of Resources Without Limits or Throttling vulnerabilities in an interactive lesson.
Start learning- Snyk IDSNYK-RUBY-MCP-18017531
- published19 Jul 2026
- disclosed17 Jul 2026
- creditHE WEI
Introduced: 17 Jul 2026
New CVE NOT AVAILABLE CWE-770 (opens in a new tab)How to fix?
Upgrade mcp to version 0.23.0 or higher.
Overview
mcp is a The official Ruby SDK for Model Context Protocol servers and clients
Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling in the handle_post method of lib/mcp/server/transports/streamable_http_transport.rb, which reads the entire HTTP request body into memory with request.body.read and then parses it via JSON.parse(body_string, symbolize_names: true) with no size limit. An attacker can exhaust worker memory and terminate the process by sending a single oversized JSON-RPC POST request, whose parsing materializes the full object graph and interns a Ruby symbol for every key. Exploitation requires only TCP connectivity to the MCP endpoint, and the vulnerable path runs before session validation, so it applies in both stateful and stateless modes.